You have altered a non-unique index to be invisible to determine if queries execute within an acceptable response time without using this index. Which two are possible if table updates are performed which affect the invisible index columns?（）
- A The index remains invisible.
- B The index is not updated by the DML statements on the indexed table.
- C The index automatically becomes visible in order to have it updated by DML on the table.
- D The index becomes unusable but the table is updated by the DML.
- E The index is updated by the DML on the table.